טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentEden Orit
SubjectSimulation and Visualization of Gravity Currents
DepartmentDepartment of Computer Science
Supervisors Professor Marius Ungarish
Professor Gershon Elber


Abstract

Gravity currents, sometimes called density currents, occur in both natural and artificial situations. These currents are generated whenever fluid of one density flows primarily horizontally into fluid of a different density.  The efficient visualization of the flow field (i.e., velocities, streamlines, density contours) of these quite complex phenomena is of interest to industrial and environmental control applications.


  This work presents a grid-independent multi-resolution algorithm for the visualization of gravity currents, which propagate over a horizontal impermeable boundary in either a rectangular or an axisymmetric geometry.  The algorithm utilizes the fact that a streamline, which is a curve that is everywhere tangent to the velocity field, is also a contour line of the stream function, and traces contours of same stream function's level over time. Multi-resolution coverage of the domain of the field is produced by recursive streamlines filling the domain while using Line Integral Convolution (LIC) as the underlying line rendering method. The streamlines coverage algorithm is able to animate gravity current unsteady flows, while demonstrating temporal coherence between animated frames. Moreover, a method for modulating an additional scalar value over the output image by controlling its contrast is also presented.


 Using the method developed in this work, researchers are now able to view 2D and 3D axisymmetric gravity currents in an efficient way. They can follow the current progress and the streamline evolution over time, choose the streamlines resolution and the type of field parameters they wish to view.